The sol-gel process is a condensation polymerization process, wherein metal alkoxides are hydrolyzed to generate intermediate species of metal hydroxides, and then the metal hydroxides undergo a stepwise polycondensation reaction to form a three dimensional network. The gelling compositions also can contain solvent and additional constituents such as metal alkoxides, polymers, and metal salts. The process has been used in the preparation of processable glasses, ceramics, optical materials and protective coatings on metals. For a further description of this process, see Sol-Gel Science The Physics and Chemistry of Sol-Gel Processing, by C. Jeffrey Brinker and George W. Scherer, 1990, Academic Press, Inc.
This disclosure describes the incorporation of suitable polymeric binders into the sol-gel process to produce a novel class of water insoluble absorbent coatings. This novel class of water insoluble absorbent coating materials comprises silica, solvent- and water-soluble polymers, and acid catalysts. The present inventive materials show unexpectedly advantageous properties for ink jet media and other applications.
No current art provides such a material. U.S. Pat. No. 5,219,928 discloses a liquid-absorbent composition that comprises cross-linked silanol moieties that are provided as part of the monomeric units used in the formation of a matrix component polymer or are grafted into the polymer after the formation of the polymeric backbone. The cross-links are limited to the matrix components that use cross-linkable polymers incorporating silanol groups therein.